title: [Preliminary study for classification of spino-pelvic sagittal alignment in adult volunteers].
abstract: OBJECTIVE
  To investigate the feasibility of the classification of the spino-pelvic sagittal alignment in adluts according to lumbar lordosis (LL) and inflection point (IP).
  
  
  METHODS
  Whole spine, standing radiographs of 223 adult volunteers were taken from July to August in 2011 .There were 111 cases(56 female and 55 male) enrolled in the study based on the inclusion criteria. The pelvic and spinal parameters, including thoracic kyphosis(TK), thoracolumbar kyphosis(TLK), LL, sacral slope(SS), pelvic tilt(PT), pelvic incidence(PI), intervertebral endplate angle, sagittal vertical axis (SVA), spino-sacral angle (SSA) and IP were measured. The spino-pelvic sagittal alignment were classified in to 3 types according to LL and IP. Type I: LL > -40°, IP located below L2 ∼ 3; Type II: -60° ≤ LL ≤ -40°, IP located in L1 ∼ 2 or T12 ∼ L1; Type III: LL < -60°, P located above T11 ∼ 12. Pearson correlation analysis was used to test the correlation between the variables. The parameters in each type were compared by oneway-ANOVA respectively,then additional multiple comparisons were performed.
  
  
  RESULTS
  The mean value of LL was -49° ± 10°, TK was 36° ± 7°, TLK was 6° ± 7°, PT was 11° ± 7°, SS was 34° ± 8°, PI was 45° ± 9°, SSA was 127° ± 9° and SVA was (-2.7 ± 22.8)mm, respectively. Only LL had significant statistical correlation with all the other parameters. Negative correlation presented between LL and TK, PI, SS, SSA (r = -0.387, -0.536, -0.858, -0.801,P < 0.05). Positive correlation presented between LL and TLK, SVA, PT (r = 0.319, 0.296, 0.262, P < 0.05). All the volunteers were classified into the 3 types: Type I1 9 cases, Type II 75 cases,Type III 17 cases. Oneway-ANOVA results showed statistical difference in LL, TK, TLK, PT, SS, PI, SSA, SVA among the 3 types, (F = 164.559, 7.431, 14.099, 4.217, 53.856, 6.252, 35.995, 8.626, P < 0.05 ). Multiple comparisons showed that LL, SS, SSA, PI had statistical difference between each two types comparison (P < 0.05).
  
  
  CONCLUSIONS
  LL is the central parameter of the spino-pelvic sagittal balance. The patterns of the spino-pelvic sagittal alignment in adults could be classified into three types, according to LL and IP. The classification could describe the morphological differences and balance of the spino-pelvic sagittal alignment.
authors.affiliation: Department of Orthopaedics, the Third Affiliated Hospital of Southern Medical University, Guangzhou 510630, China.
authors.forename: Gang-Hui
authors.initials: GH
authors.lastname: Yin
authors.forename: Ling-Xiang
authors.initials: LX
authors.lastname: Zhu
authors.forename: Rui-Song
authors.initials: RS
authors.lastname: Chen
authors.forename: Zhi-de
authors.initials: ZD
authors.lastname: Lü
authors.forename: Ming
authors.initials: M
authors.lastname: Lu
authors.forename: Hui-Bo
authors.initials: HB
authors.lastname: Yan
authors.forename: Zhong-Min
authors.initials: ZM
authors.lastname: Zhang
authors.forename: Qing-Chu
authors.initials: QC
authors.lastname: Li
authors.forename: Da-di
authors.initials: DD
authors.lastname: Jin
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D000886:Anthropometry; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D008875:Middle Aged; D010388:Pelvis / Q000033:anatomy & histology*; D004856:Postural Balance; D011859:Radiography; D013131:Spine / Q000033:anatomy & histology*